<template>
    <div class="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
<script>
export default {
    name: 'SIdentify',
    props: {
        identifyCode: {
            type: String,
            default: ''
        },
    },
    data() {
        return {
            fontSizeMin: 30,
            fontSizeMax: 40,
            backgroundColorMin: 180,
            backgroundColorMax: 200,
            colorMin: 50,
            colorMax: 100,
            lineColorMin: 40,
            lineColorMax: 100,
            dotColorMin: 0,
            dotColorMax: 100,
            contentWidth: 112,
            contentHeight: 38
        }
    },
    methods: {
        // 生成一个随机数
        randomNum(min, max) {
            return Math.floor(Math.random() * (max - min) + min)
        },
        // 生成一个随机的颜色
        randomColor(min, max) {
            let r = this.randomNum(min, max)
            let g = this.randomNum(min, max)
            let b = this.randomNum(min, max)
            return 'rgb(' + r + ',' + g + ',' + b + ')'
        },
        drawPic() {
            let canvas = document.getElementById('s-canvas')
            let ctx = canvas.getContext('2d')
            // ctx.textBaseline = 'bottom'
            // 绘制背景
            ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax) //图形填充颜色设置
            ctx.strokeStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax) //图形轮廓的颜色设置
            ctx.fillRect(0, 0, this.contentWidth, this.contentHeight) //绘制一个填充的矩形 0 0 width height x起点 y起点  宽 高
            ctx.strokeRect(0, 0, this.contentWidth, this.contentHeight) // 绘制一个矩形边框 0 0 width height x起点 y起点  宽 高
            // ctx.clearRect(50,0,this.contentWidth,this.contentHeight)  //清除指定矩形区域，清除部分完全透明
            // 绘制文字
            for (let i = 0; i < this.identifyCode.length; i++) {
                this.drawText(ctx, this.identifyCode[i], i)
            }
            // this.drawLine(ctx)
            this.drawDot(ctx)
        },
        drawText(ctx, txt, i) {
            ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
            ctx.font = this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei' //字体大小
            ctx.textBaseline = 'alphabetic' //基线对齐
            let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
            let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
            var deg = this.randomNum(-15, 15)
            // 修改坐标原点和旋转角度
            ctx.translate(x, y)//移动不同位置  参数偏移量
            ctx.rotate(deg * Math.PI / 180) //旋转 参数角度
            ctx.fillText(txt, 0, 0)
            // 恢复坐标原点和旋转角度
            ctx.rotate(-deg * Math.PI / 180)
            ctx.translate(-x, -y)
        },
        drawLine(ctx) {
            // 绘制干扰线
            for (let i = 0; i < 6; i++) {
                ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
                ctx.beginPath() //新建一条路径
                ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight)) //设置起点x,y
                ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight)) //绘制直线 x,y 一条当前位置到x,y点的直线
                ctx.stroke() // 通过线条绘制图形轮廓
                // ctx.closePath() //结束闭合路径
            }
        },
        drawDot(ctx) {
            // 绘制干扰点
            for (let i = 0; i < 50; i++) {
                ctx.fillStyle = this.randomColor(0, 255)
                ctx.beginPath()
                // 绘制圆弧或圆，x,y,radius，startAngle,endAngle,anticlockwise // x,y 圆心点，radius 半径，从startAngle开始到endAngle结束
                ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI)
                ctx.fill() //通过填充路径的内容区域生成实心的图形。
            }
        }
    },
    watch: {
        identifyCode: function(){
            this.drawPic()
        }
    },
    mounted() {
        this.drawPic()
    }
}
</script>

